As a result of this program of systematic research, we now have reasonable evidence that cannabis is a promising treatment in selected pain syndromes caused by injury or diseases of the nervous system, and possibly for painful muscle spasticity due to multiple sclerosis.

Participants in the study reported negative side effects of cough, dizziness, sedation and changes in cognition, the results reveal.

Medical marijuana patients and advocates have been touting its benefits for years, even without such an in-depth study. Even with strong support from medical professionals, pot will remain a hot topic in politics. One of the goals of the study, the group says, is to help give lawmakers a clearer picture about the benefits of the natural medicine.

Medical marijuana has been legal under California law since voters approved Proposition 215, also known as the Compassionate Use Act, in 1996.